In computer operation, especially personal computer operation, it is often desirable to utilize peripheral devices known as modems which allow a computer to send an receive data across conventional telephone lines. As known in the art, and to most users of computers, modems (a contraction for modulator/demodulator) are devices which convert digital signals from a computer or terminal into a modulated signal appropriate for transmission across conventional telephone lines. Most modems for personal computers use a modulation technique which is appropriate for transmission over the relatively narrow usable bandwidth of conventional phone lines.
Many personal computers in use today utilize a hardware architecture by which peripheral devices are connected to expansion slots on the mother board of the computer, as opposed to serial or parallel ports with plug connections which are external to the computer cover. A number of peripherals or expansion devices may be inserted into the expansion slots and the normal cover for the computer may then be replaced. This arrangement allows the user to expand the capabilities of the computer without a corresponding expansion of the number of boxes and cables lying about the computer installation site.
In the marketing of personal computers, a trade-off is often necessary between the physical size of the compound and the number of expansion slots made available to the user. Therefore, inter-slot spacing in such computers is kept to a practical minimum. Modems and other devices constructed upon a single circuit board which occupy only a single expansion slot of a small computer are desired by users.
It is known in the art to provide such "internal" modems of varying degrees of sophistication upon a single circuit board installed within a single expansion slot of a small computer. However, often a consumer who has bought a relatively low-level modem may desire to upgrade the modem's capabilities. This creates a dilemma in that the old low-level modem is effectively rendered obsolete, as an entirely new circuit board is required to be installed in place of the old circuit board. This is disadvantageous in that the old low-level circuit board tends to have a low resale value, and is often of little further use to the upgraded user.
Therefore, it may be seen that a need exists for a circuit board configuration which allows for a space- and cost-effective manner of upgrading modem capabilities.